Problem: 8 rubber stamps cost $12.48. Which equation would help determine the cost of 3 rubber stamps?
There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 8 rubber stamps. We want to know the cost of 3 rubber stamps. We can write the numbers of rubber stamps as a proportion: $\dfrac{8}{3}$ We know 8 rubber stamps costs $12.48. We can let $x$ represent the unknown cost of 3 rubber stamps. The proportion of these costs can be expressed as: $\dfrac{\$12.48}{x}$ The cost changes along with the number of rubber stamps purchased, and so the two proportions are equivalent. $\dfrac{8}{3} = \dfrac{\$12.48}{x}$